Steel X75WCrV18-4-1 QT64-66 vs X75WCrV18-4-1-SR
Steel · X75WCrV18-4-1 temper comparison
X75WCrV18-4-1 QT64-66 and X75WCrV18-4-1-SR are two conditions of the same steel grade, X75WCrV18-4-1: QT64-66 (QT 64–66 HRC) versus SR (stress relieved). The chemistry is identical, so every difference below comes from the condition. X75WCrV18-4-1 QT64-66 is the stronger of the two: yield strength 2,000 MPa (290 ksi) against 570 MPa (82.7 ksi) for X75WCrV18-4-1-SR, about 3.5 times as much; tensile strength follows at 2,200 MPa (319 ksi) vs 910 MPa (132 ksi). In exchange, X75WCrV18-4-1-SR is the more ductile: elongation 12% versus 0.5% for X75WCrV18-4-1 QT64-66, and X75WCrV18-4-1 QT64-66 is harder (65 HRC vs 24 HRC). X75WCrV18-4-1 QT64-66 runs hotter in service (600°C vs 400°C continuous). On the shop floor, X75WCrV18-4-1-SR machines more easily (poor vs not recommended) and X75WCrV18-4-1-SR welds better (poor vs not recommended).
X75WCrV18-4-1 QT64-66Choose it when strength drives the design, or when the part sees heat.
X75WCrV18-4-1-SRChoose it when the part is bent, formed or impact-loaded, or when the part is machined in volume.
X75WCrV18-4-1 QT64-66 vs X75WCrV18-4-1-SR: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all steel grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
X75WCrV18-4-1 QT64-66X75WCrV18-4-1-SR
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Yield Strength (0.2% offset)
Elongation at Break
Reduction in Area
Compressive Strength
Shear Strength
Charpy V-Notch Impact (RT)
Hardness, Brinell
Hardness, Rockwell C
Hardness, Vickers
Same in both: Elastic (Young's) Modulus 220 GPa31.9 Msi · Shear Modulus 85 GPa12.3 Msi · Bulk Modulus 165 GPa23.9 Msi · Poisson's Ratio 0.29
Physical
Density and transition temperatures.
Same in both: Density 8.7 g/cm³0.31 lb/in³ · Melting Point (Solidus) 1,250°C2,282 °F · Liquidus Temperature 1,420°C2,588 °F
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Max Service Temperature (continuous)
Same in both: Specific Heat Capacity 420 J/kg·K0.1 BTU/lb·°F · Thermal Expansion (CTE, 20–100 °C) 11 µm/m·K6.1 µin/in·°F · Latent Heat of Fusion 250 J/g107 BTU/lb · Min Service Temperature -60°C-76 °F
Electrical
Conductivity and insulation.
Electrical Conductivity
Electrical Resistivity
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Machinability
Machinability Rating (AISI 1212 = 100 %)
Weldability
Formability (cold)
Same in both: Castability 30 / 100 · Brazeability / Solderability 55 / 100 · Polishability 70 / 100
Sustainability
Primary-production footprint per kilogram.
Same in both: Embodied Energy (primary production) 58 MJ/kg24,936 BTU/lb · Embodied Carbon (primary production) 4.2 kg CO₂/kg · Embodied Water 90 L/kg10.8 gal/lb · Typical Recycled Content 30%
Strength versus weight
Yield strength against density for every steel grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
X75WCrV18-4-1 QT64-66 vs X75WCrV18-4-1-SR — frequently asked
Is X75WCrV18-4-1 QT64-66 stronger than X75WCrV18-4-1-SR?
Yes. X75WCrV18-4-1 QT64-66 has a typical yield strength of 2,000 MPa (290 ksi) against 570 MPa (82.7 ksi) for X75WCrV18-4-1-SR — about 3.5 times as much. Tensile strength is 2,200 MPa (319 ksi) vs 910 MPa (132 ksi).
Which condition does FabDigit quote by default, QT64-66 or SR?
A is the default X75WCrV18-4-1 condition in the FabDigit quote flow (neither QT64-66 nor SR). The other condition is available on request or by drawing note — specify it in the material field or the part notes and the quote is priced for it.
Which is easier to machine, X75WCrV18-4-1 QT64-66 or X75WCrV18-4-1-SR?
X75WCrV18-4-1-SR. Its machinability rates poor (33/100) against not recommended (5/100) for X75WCrV18-4-1 QT64-66; for welding the order is X75WCrV18-4-1-SR first (poor, 20/100) then X75WCrV18-4-1 QT64-66 (not recommended, 5/100).
Ready to make it?
Upload a CAD file and FabDigit prices the part in X75WCrV18-4-1 QT64-66 and X75WCrV18-4-1-SR side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.